AeroRocketCAD for
Airframe & Nozzle Shapes 
AeroRocketCAD
Convert AutoCAD DXF Drawing Files
to AeroRocket ImportShape Formats
GO
...
&
AeroGRID
Generate Fluid Boundary Shapes
for AeroCFD, AeroWindTunnel and Nozzle
GO
...

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Copyright © 19992015 John Cipolla/AeroRocket. All rights
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AeroRocketCAD converts
AutoCAD DXF drawing file LINE and ARC entities
to importshape file formats for AeroCFD, Nozzle and
AeroWindTunnel. This program is provided FREE of charge for purchasers of
all AeroRocket fluid dynamics programs that utilize 2D and 3D
importshape geometry.
Also, quickly
generate fluid boundary surfaces using the new AeroGRID design utility by
generating TOP and SIDE views of realistic 3D airframes for AeroWindTunnel or complex
3D axisymmetric and 2D shapes
for AeroCFD and Nozzle. 
AeroRocketCAD (TOP)
Figure1, DXF conversion as it appears after clicking, Open
DXF Geometry using Zoom then using XTRANSLATION
and YTRANSLATION
DXF
FILE CONVERSION (SEE FIGURE1 AND FIGURE2
1) To Open and convert an AutoCAD .DXF drawing file, click File then click Open DXF Geometry.
Please see Figure1.
2) Find and click a .DXF drawing file previously
created by AutoCAD. AutoCAD generated LINES and ARCS
will appear in the lower left of the plot area.
3) Use ZOOM to enlarge the drawing and to make
all segment numbers visible. If required use
XTRANSLATION and YTRANSLATION to make all
segment numbers visible. Please see Figure1.
4) In Highlight segments insert segment numbers
that represent the fluid boundary. Use Highlight
segments to note the location of all drawing file
LINE and ARC entities that appear in the
converted AutoCAD DXF drawing file. Please see Figure1.
5) In the Vertical Text Box, enter LINE
and ARC segment numbers that define the fluid
boundary. The numbering sequence must be from left to
right. However, it should not matter in what sequence
the curves were generated in AutoCAD. Use CLEAR
to start over. Simply backspacing will confuse the
program and unpredictable shapes will occur. CLEAR
must be used to start over. Remember, insert each
segment number and then click Enter. Please see
Figure1.
6) To generate a AeroCFD, Nozzle etc. fluid boundary
click the Generate fluid boundary in converted
coordinates option button. No fluid boundary will be
generated until the segment numbers are input using the
procedure outlined in item 5. Please see Figure2.
7) Click File then Save XXX Geometry As
... to save the converted shape as an import file
for use with AeroCFD, Nozzle, etc. Please see
Figure2.
8) When initially
importing a new shape into AeroCFD, click File
then Import Shape to input a geometry file created in AeroRocketCAD. Then,
in AeroCFD define the flow and mesh parameters and save the project file by
clicking File then Save Project As. Subsequently, to run a project
and its associated airframe shape the shape file is imported first and then the project
file is opened. Running a previously saved shapeproject is performed by first
clicking File then Import Shape and finally by clicking Open
Project. Please wait for the shape and mesh parameters to be generated
before performing each step. The data has the following format. First line:
Total number of XY point locations, maximum of 1000 points. Second and subsequent lines: X, Y airframe
locations separated by commas. A AeroCFD shape file defines the upper contour
of an axisymmetric airframe geometry starting from nosetip to the end of
the airframe.
9) Please see the AeroCFD analysis that generates the
geometry of a
Coke Bottle
using DXF formatted data.
OPTIONAL INPUT DATA
9) Identify each .DXF drawing file segment by inserting
individual segment (curve) numbers into the Highlight
segments data entry box.
10) In the Number of grid points per segment data
entry box increase or
decrease the number of grid points on each fluid
boundary segment by inserting a new number of grid
points.
11) Make the generated surface an Internal flow
boundary for Nozzle by checking the bottom most check
box. If the check box is unchecked the surface is an External
boundary (AeroCFD, AeroEuler) and if the check box is checked the surface is an
Internal boundary (Nozzle). 
Figure2, DXF conversion as it appears after entering segment
numbers 6,2,3,4,5 then clicking the Generate fluid boundary
in converted coordinates option button
AeroGRID (TOP)
AeroGRID
is a standalone computer program accessed from within
AeroRocketCAD used to generate fluid
boundary shapes by specifying the TOP View and
SIDE View for AeroWindTunnel or complex
axisymmetric and twodimensional fluid boundary shapes for
AeroCFD and Nozzle. 
Figure3, AeroGRID generated shape using four grid
points and Cubic Spline smoothing. This shape was successfully run
in AeroCFD at Mach 2
AEROGRID
FLUID BOUNDARY GENERATION
1) To generate a fluid boundary for AeroCFD, AeroWindTunnel or Nozzle without a DXF drawing
file, in the top pull down menu click Number of Grid Points
then select the number of grid points required to define a
fluid boundary. 2 to 20 grid points may be selected using
the pull down menu. Please see Figure3.
2) In Total Length (X) specify the total length of
the fluid boundary. This length represents total airframe
length for AeroCFD and AeroWindTunnel or total nozzle
length for the Nozzle program.
3) Using the Point number option buttons and the
YCOORDINATES slider bar define a fluid boundary shape
for the number of grid points selected.
4) After the shape is specified use the Generate fluid
boundary using interior points option button to plot the
resulting fluid boundary grid points.
5) Change the number of grid points on each segment of the
fluid boundary by inserting a new value in the Number of
interior grid points per segment data entry box from the default value
of 20 to any number ranging from 2 to 1000. Remember, the total
number of grid points on the fluid boundary is limited to
1000 because of program (AeroCFD, Nozzle, etc)
limitations.
6) Click File then Save XXX Geometry As
... to save the fluid boundary shape as an import file
for AeroCFD, Nozzle, etc. Please see
Figure3.
7) Click the SMOOTH CURVE command button to smooth
the fluid boundary using a Cubic Spline curve fit of
the available grid points. See Figure4.
AEROWINDTUNNEL AIRFRAME GENERATION
8) Repeat STEP1 and STEP2 as before. Then, use the Point number option buttons
and the YCOORDINATES slider bar to define the TOP
View for imported airframes. Then, in the
bottom section click the Generate airframe
PLAN view (top) option button when one half of
the TOP View is specified. SMOOTH curve if required. The TOP
view is now specified.
9) Then, using the Point number option buttons and
the YCOORDINATES slider bar define the UPPER part of
the airframe SIDE View. Then, click the Generate airframe
UPPER side view (+height) option button when the
upper half of the airframe SIDE View is specified.
SMOOTH curve if required. The upper half of the side view is
now specified.
10) Then, using the Point number option buttons and
the YCOORDINATES slider bar define the LOWER part of
the airframe SIDE View. Then, click the Generate airframe
LOWER side view (height) option button when the
lower half of the airframe SIDE View is specified.
SMOOTH curve if required. The lower half of the side view is
now specified.
11) Finally, to save the AeroWindTunnel airframe geometry first
click File then, Save AeroWindTunnel Geometry As
... Please see Figure3.
Please note every time the Point number option
buttons and the YCOORDINATES slider bar are modified
a new TOP/SIDE View may be specified. 
Figure4, AeroGRID generated shape using three grid
points and Cubic Spline smoothing for generating AeroWindTunnel TOP
View
Figure5, AeroGRID generated shape using three grid
points and Cubic Spline smoothing for generating AeroWindTunnel
UPPER side View
Figure6, AeroGRID generated shape using three grid
points and Cubic Spline smoothing for generating AeroWindTunnel
LOWER side View
Figure7, AeroWindTunnel screen after importing AeroGRID
shape file
NOZZLE
FLUID BOUNDARY GENERATION
1) To generate a fluid boundary for Nozzle without a DXF drawing
file, in the top pull down menu click Number of Grid Points
then select the number of grid points required to define a
fluid boundary. 2 to 20 grid points may be selected using
the pull down menu. Please see Figure8.
2) In Total Length (X) specify the total length of
the nozzle fluid boundary. This length represents total
nozzle length.
3) Using the Point number option buttons and the
YCOORDINATES slider bar define a fluid boundary shape
for the number of grid points selected.
4) After the shape is specified use the Generate fluid
boundary using interior points option button to plot the
resulting fluid boundary grid points.
5) Change the number of grid points on each segment of the
fluid boundary by inserting a new value in the Number of
interior grid points per segment data entry box from the default value
of 20 to any number ranging from 2 to 1000. Remember, the total
number of grid points on the fluid boundary is limited to
1000 because of program Nozzle
limitations.
6) Click File then Save XXX Geometry As
... to save the fluid boundary shape as an import file
for Nozzle.
7) Click the SMOOTH CURVE command button (optional) to smooth
the fluid boundary using a Cubic Spline curve fit of
the available grid points.

Figure8, AeroGRID shape using four grid points for generating
Nozzle boundary shape
Figure9, Nozzle screen after importing AeroGRID
boundary
shape file
Figure10, AeroGRID uses Cubic Spline smoothing to
connect
nonsmooth fluid boundary segments
The Cubic
Spline used in AeroGRID is a method to draw a smooth
curve through specified endpoints as if using a French
curve or a draftsman's spline. Smoothing coefficients allow
the combined fitting function F(x) to be a combination of
smoothly joined cubic segments, f(x). If the combined
fitting curve is called F(x), then F(x) is represented by n
segments [f_{i}(x), i = 0, n  1] each of which can
be written as f_{i}(x) = a_{0i} + a_{1i}(xx_{i})
+ a_{2i}(xx_{i})^{2 }+ a_{3i}(xx_{i})^{3
}for x_{i} < x < x_{i+1} and i = 0, n 
1. Save AeroGRID's Cubic Spine smoothing coefficients by
clicking File then Save Smoothing Coefficients As
... Please see Figure3 and Figure4. 
REFERENCES
AutoCAD 2009
DXF Reference manual by Autodesk
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